After five hours of waiting Heather and her son Sandy were nearly thereImage caption: After five hours of waiting Heather and her son Sandy were nearly there
Heather, 56, and her son Sandy Rippon, 20, joined the Queen’s vigil queue on Monday evening.
After five-and-a-half hours in line, they were approaching the cathedral with sandwiches and cold drinks in hand for the final stretch.
Heather, who is from Northern Ireland but lives in Peebles in the Scottish Borders, said of the wait: "It's not been too bad.
"We've spoken to a few interesting people in the queue, including a lady whose mum used to do Highland dancing at Braemar."
"We're here because it's the right thing to do," says Heather.
"She's been our Queen all our lives and we've never known anyone different."
Foreign leaders asked to catch bus to funeral - report
The Queen's funeral is likely to be one of the largest and most significant international events the UK has hosted for decades. Leaders from around the world are invited to Westminster Abbey for the ceremony on Monday 19 September.
Media reports, however, suggest the UK Foreign Office has issued documents for those attending asking them to arrive by commercial jets, not private ones, and even requiring leaders to catch buses en masse from a site in west London, instead of using their own cars.
According to news website Politico, countries have been asked to keep their delegations to the funeral as small as possible, with only the head of state and their spouse invited to the funeral itself.
And private jet and car rules are in place to prevent London's airports and streets becoming swamped by the sheer numbers of those arriving.
US President Joe Biden has confirmed he will attend the event in person. The Guardian newspaper reports that a spokesperson for UK Prime Minister Liz Truss said on Monday that "arrangements for different leaders will vary", and that the documents were only for guidance.
Mourners queue for hours
Kirsty Wark
Outside St Giles' Cathedral in Edinburgh
ReutersCopyright: Reuters
The queues go right round Parliament Square in front of the Signet Library, by St Giles' Cathedral.
People aren’t taking very long to go through. They’ve waited
for hours and hours, but they’re moving quite swiftly.
Inside the cathedral, the coffin of
Queen Elizabeth II lies on the catafalque, with the crown of Scotland at the head towards the front of the coffin.
People are very respectful. Some have been shedding
tears. Some people stopping, showing their children, as if they want them
to know about this history. One man can be seen carrying a baby in his arms
past the Queen’s coffin.
I was struck by older people going past, some
infirm, who have waited for such a long time. And it meant so much to them
because she has been monarch for most of their lives.
'Met police have monumental task' - ex-Secret Service agent
Timothy Miller, a security specialist and former US Secret Service agent, told the BBC that the Metropolitan Police have a "monumental task ahead of them" for the Queen's funeral.
When asked about whether US President Joe Biden would be travelling without Air Force One or his motorcade, he said it was not a "realistic possibility".
"The president of the US must be able to react within minutes to potential threats against the nation. As the leader that he is, he must have access to Air Force One for a number of security reasons, but also motorcade travel is important. The Secret Service is very sensitive on the requirements that they have," he told the World Tonight programme.
Miller said there would be unique security challenges.
"There will be a lot of heads of state in a single location and that's a dangerous security situation." he said.
Watch: How the day unfolded
Speeches at Westminster and Holyrood, a procession through the streets of Edinburgh, and queues to see the Queen at St Giles' Cathedral - it's been another hectic day.
You can watch a full round-up of all Monday's events here:
Video content
Video caption: How the day unfolded - in 90 secondsHow the day unfolded - in 90 seconds
Night trains during Queen mourning period
Katy Austin
Transport correspondent
The group that represents train companies has confirmed trains will run through the night on some routes to help people travel to pay their respects to the late Queen, but that this offer will be "very limited".
A Rail Delivery Group spokesperson said: "The rail industry is doing all it can to ensure people can travel to pay their respects during the period of mourning.
"Where possible we will be running some extra services and customers should check journey planners for the most up to date information."
On night trains specifically: "A very limited service will be operating through the night on some routes, people should check journey planners for details."
It’s not currently clear exactly when this period will start or end.
Man arrested in Edinburgh after procession
Police Scotland have announced that a 22-year-old man was arrested on Monday in connection with a breach of the peace on the Royal Mile in Edinburgh.
Footage posted on social media show a man yelling at the funeral procession through Scotland's capital, which included all four of the Queen's children.
After heckling the procession he was pulled back and removed from the crowd by police.
It's not the only incident involving demonstrators. A woman bearing a sign reading "Not my King" was moved away from the Palace of Westminster by officers on Monday, while a 22-year-old woman was arrested outside Edinburgh's St Giles' Cathedral on Sunday.
She has been released from custody but is due in court at a later date.
Getty ImagesCopyright: Getty Images
Officers move the demonstrator on from the Palace of Westminster in LondonImage caption: Officers move the demonstrator on from the Palace of Westminster in London
Queen was bright and focused in last audience - Boris Johnson
Video content
Video caption: Boris Johnson recalls final meeting with the QueenBoris Johnson recalls final meeting with the Queen
The former Prime Minister Boris Johnson has told the BBC the Queen was "absolutely on it" in their last meeting before his resignation as prime minister last week, just two days before her death.
"She was actively focused on geopolitics, on UK politics, quoting statesmen from the '50s, it was quite extraordinary. And she seemed very bright, very focused," he told BBC presenter Fiona Bruce.
"Given how ill she obviously was, how amazing it was that she be so bright and focused. It was a pretty emotional time."
When her death was announced two days later, he said he was moved by the Queen's "sense of duty".
Scotland's First Minister Nicola Sturgeon greeted the new King at the Scottish ParliamentImage caption: Scotland's First Minister Nicola Sturgeon greeted the new King at the Scottish Parliament
That the King has chosen to begin his reign with visits to Edinburgh, Belfast and
Cardiff is telling.
It suggests that the future of the Union is at the heart of
his concerns.
The early decades of his late mother's reign were characterised
by the long, slow contraction of British Imperial power around the world.
He
will be alert to the possibility that his own reign could come to be defined by
the continuation of that process here - and the eventual dissolution of the
United Kingdom itself.
Watch: King and siblings hold vigil by Queen's coffin
Video content
Video caption: The Queen's children perform what's known as the Vigil of the PrincesThe Queen's children perform what's known as the Vigil of the Princes
The Queen's children carried out the traditional Vigil of the Princes around the coffin of their late mother in St Giles' Cathedral, Edinburgh, earlier this evening.
The symbolic move sees four people position themselves at each side of the coffin to stand guard for a short time - today's event lasted 10 minutes.
King Charles III took up the role alongside his three siblings, the Princess Royal, the Duke of York and the Earl of Wessex.
What happens next?
Following the Vigil of the Princes, the Queen's coffin will continue to rest at St Giles' Cathedral in Edinburgh until 17:00 BST on Tuesday.
It will be moved from Edinburgh to the city's airport, where it will then be flown to RAF Northolt in west London at 18:00.
The Princess Royal, Princess Anne, will accompany the coffin, as she has since the beginning of its journey from Balmoral.
The coffin is expected to arrive in London at 19:00, and will then travel to Buckingham Palace, where it will be met by King Charles III and Camilla, Queen Consort.
BBCCopyright: BBC
The King and his wife will continue their tour of the nations tomorrow by visiting Belfast, where the monarch will meet Secretary of State for Northern Ireland, Chris Heaton-Harris, as well as other party leaders.
After a meeting with religious leaders, the royal couple will attend a prayer service at St Anne's Cathedral before travelling to London.
You can read about the day's proceedings in more detail here.
Mourners 'extremely moved' by moment beside the Queen's coffin
BBCCopyright: BBC
About 20,000 people have been waiting in a mile-long queue for several hours to enter St Giles' Cathedral in Edinburgh, where the Queen's coffin lies at rest.
William MacDonald, 63, from Edinburgh, says he was "extremely moved" by the experience of finally getting to pay his respects.
“It was beautiful,” he says. “Everything was done so well. I will never forget it. It was mind-blowing.
“She has been the best Briton ever, along with Winston Churchill.
"I am a bit star-struck.”
Rodney Matthews, a retired Baptist minister and member of Old Saint Paul's, a Scottish Episcopal Church in the heart of Edinburgh, says there was a sense of serenity about the event.
BBCCopyright: BBC
“You were able to move very slowly through, there was no rush at all," he says.
“There’s a moment where you can actually stand there and take it all in, the dignity of the whole place.
“It was very well done, very well organised once you go through security and get that feeling of space.”
In pictures: Charles, Anne, Andrew and Edward stand vigil
PA MediaCopyright: PA Media
Members of the public file past as the Queen's children stand is silence alongside their mother's coffinImage caption: Members of the public file past as the Queen's children stand is silence alongside their mother's coffin
After a poignant 10 minutes, the vigil has now come to an end, with the Royal Family returning to their cars to applause from the crowd outside the cathedral.
BBCCopyright: BBC
All four of the Queen's children - including King Charles III - stood around her coffin in EdinburghImage caption: All four of the Queen's children - including King Charles III - stood around her coffin in Edinburgh
BBCCopyright: BBC
The Princess Royal is the first woman to take part in the Vigil of the PrincesImage caption: The Princess Royal is the first woman to take part in the Vigil of the Princes
BBCCopyright: BBC
The Duke of York, Prince Andrew, closes his eyes during the vigilImage caption: The Duke of York, Prince Andrew, closes his eyes during the vigil
BBCCopyright: BBC
The Earl of Wessex, Prince Edward, stands beside his mother's coffinImage caption: The Earl of Wessex, Prince Edward, stands beside his mother's coffin
The Queen's children take their places
BBCCopyright: BBC
King Charles III (far right), Princess Anne (centre), Prince Andrew (far left) and Prince Edward (back centre) - the Queen's four children - stand guard around her coffinImage caption: King Charles III (far right), Princess Anne (centre), Prince Andrew (far left) and Prince Edward (back centre) - the Queen's four children - stand guard around her coffin
As we reported earlier, the Queen's four children are performing the traditional Vigil of the Princes around the coffin of their late mother at St Giles' Cathedral.
The symbolic move sees four people - in this case King Charles III, Princess Anne and Princes Andrew and Edward - position themselves at each side of the coffin to stand guard for a short time.
The Princess Royal's appearance makes her the first woman to be part of the vigil, which has until now been carried out by male-only members of the Royal Family.
When the Queen Mother died, her four grandsons carried out the duty - Charles, Andrew, Edward and David Armstrong-Jones, Princess Margaret's only son.
King and Queen Consort arrive for vigil
King Charles III and Camilla, Queen Consort, are now arriving at St Giles' Cathedral where they will hold a vigil for the Queen.
BBCCopyright: BBC
Huge policing effort for UK-wide events
Frank Gardner
BBC News, Security Correspondent
PA MediaCopyright: PA Media
We've seen big crowds in Edinburgh today as the Queen lies at rest in St Giles' Cathedral - and yet more are expected once her coffin arrives to London tomorrow.
The primary concern for the police and security services over the coming days is public order rather than a terrorist threat.
The Metropolitan Police is leading on this, working closely with Police
Scotland and the security service, MI5. They have rehearsed extensively for
this week.
The current UK terror threat level remains at "substantial", meaning a terrorist attack is thought to be likely, but not highly likely or imminent - which would be two levels above where we are
now.
The police are not aware of any specific terrorist threat to events
marking the death of the Queen and there has been no noticeable increase in
chatter amongst extremist groups or individuals.
That said, I’m told "no-one is going to breathe easy
until these events are behind us" - and a number of Armed Response Vehicles (ARVs) are parked up
in side roads in central London.
Tears and hugs as mourners file past Queen's coffin
A stream of mourners has been queueing in the late summer sunshine to enter St Giles' Cathedral in Edinburgh, where the Queen's coffin lies at rest.
They collected wristbands about a mile away at a station in The Meadows park earlier on, before queueing through the main University of Edinburgh area of the city to reach the cathedral.
ReutersCopyright: Reuters
ReutersCopyright: Reuters
EPACopyright: EPA
ReutersCopyright: Reuters
King Charles to stand vigil by mother's coffin
PA MediaCopyright: PA Media
Charles stands vigil by his grandmother the Queen Mother's coffin in 2002Image caption: Charles stands vigil by his grandmother the Queen Mother's coffin in 2002
Coming up, King Charles III will be back at St Giles' Cathedral in Edinburgh to hold a vigil for his late mother.
He'll stand by one corner of the raised platform - or catafalque - that her coffin is resting on. His siblings are expected to position themselves at the other three.
The process - called the Vigil of the Princes - was first carried out in 1936 when King Edward VIII and his three brothers, Princes Albert, Henry and George, stood by the coffin of their late father, King George V.
Since then, it has only been done on one other occasion - at the funeral of the Queen Mother in 2002. The King - who was known then as Prince Charles - was one of the people who stood by on that occasion.
Watch: Queen's coffin placed in St Giles' Cathedral
Video content
Video caption: Royal Regiment place Queen's coffin on catafalqueRoyal Regiment place Queen's coffin on catafalque
The Queen's coffin is now at rest on a catafalque - a raised platform - in St Giles' Cathedral, Edinburgh.
It was carried in, after the procession down the Royal Mile, by the Royal Regiment of Scotland.
Mourners begin to see Queen's coffin
BBCCopyright: BBC
This is the moment some in Edinburgh have been waiting for all day - the chance to view the Queen's coffin and pay their respects.
Wheelchair users have been given priority and have begun entering the cathedral.
Some people have been queueing since before 7am to ensure they get a wristband.
Officers of the King's Body Guard for Scotland are standing guard around the Queen's coffin - King Charles will stand vigil next to it later this evening.
Live Reporting
Edited by Jude Sheerin
All times stated are UK
New 
BBCCopyright: BBC After five hours of waiting Heather and her son Sandy were nearly thereImage caption: After five hours of waiting Heather and her son Sandy were nearly there 

ReutersCopyright: Reuters Video caption: How the day unfolded - in 90 secondsHow the day unfolded - in 90 seconds Video caption: Boris Johnson recalls final meeting with the QueenBoris Johnson recalls final meeting with the Queen 
PA MediaCopyright: PA Media Scotland's First Minister Nicola Sturgeon greeted the new King at the Scottish ParliamentImage caption: Scotland's First Minister Nicola Sturgeon greeted the new King at the Scottish Parliament Video caption: The Queen's children perform what's known as the Vigil of the PrincesThe Queen's children perform what's known as the Vigil of the Princes 
BBCCopyright: BBC 
BBCCopyright: BBC 
BBCCopyright: BBC 
PA MediaCopyright: PA Media Members of the public file past as the Queen's children stand is silence alongside their mother's coffinImage caption: Members of the public file past as the Queen's children stand is silence alongside their mother's coffin 
BBCCopyright: BBC King Charles III (far right), Princess Anne (centre), Prince Andrew (far left) and Prince Edward (back centre) - the Queen's four children - stand guard around her coffinImage caption: King Charles III (far right), Princess Anne (centre), Prince Andrew (far left) and Prince Edward (back centre) - the Queen's four children - stand guard around her coffin 
BBCCopyright: BBC 

PA MediaCopyright: PA Media 
ReutersCopyright: Reuters 
ReutersCopyright: Reuters 
EPACopyright: EPA 
ReutersCopyright: Reuters 
PA MediaCopyright: PA Media Charles stands vigil by his grandmother the Queen Mother's coffin in 2002Image caption: Charles stands vigil by his grandmother the Queen Mother's coffin in 2002 Video caption: Royal Regiment place Queen's coffin on catafalqueRoyal Regiment place Queen's coffin on catafalque 
BBCCopyright: BBC
Latest Post'We're here because it's the right thing to do'
Katy Scott
BBC Scotland news
Heather, 56, and her son Sandy Rippon, 20, joined the Queen’s vigil queue on Monday evening.
After five-and-a-half hours in line, they were approaching the cathedral with sandwiches and cold drinks in hand for the final stretch.
Heather, who is from Northern Ireland but lives in Peebles in the Scottish Borders, said of the wait: "It's not been too bad.
"We've spoken to a few interesting people in the queue, including a lady whose mum used to do Highland dancing at Braemar."
"We're here because it's the right thing to do," says Heather.
"She's been our Queen all our lives and we've never known anyone different."
Foreign leaders asked to catch bus to funeral - report
The Queen's funeral is likely to be one of the largest and most significant international events the UK has hosted for decades. Leaders from around the world are invited to Westminster Abbey for the ceremony on Monday 19 September.
Media reports, however, suggest the UK Foreign Office has issued documents for those attending asking them to arrive by commercial jets, not private ones, and even requiring leaders to catch buses en masse from a site in west London, instead of using their own cars.
According to news website Politico, countries have been asked to keep their delegations to the funeral as small as possible, with only the head of state and their spouse invited to the funeral itself.
And private jet and car rules are in place to prevent London's airports and streets becoming swamped by the sheer numbers of those arriving.
US President Joe Biden has confirmed he will attend the event in person. The Guardian newspaper reports that a spokesperson for UK Prime Minister Liz Truss said on Monday that "arrangements for different leaders will vary", and that the documents were only for guidance.
Mourners queue for hours
Kirsty Wark
Outside St Giles' Cathedral in Edinburgh
The queues go right round Parliament Square in front of the Signet Library, by St Giles' Cathedral.
People aren’t taking very long to go through. They’ve waited for hours and hours, but they’re moving quite swiftly.
Inside the cathedral, the coffin of Queen Elizabeth II lies on the catafalque, with the crown of Scotland at the head towards the front of the coffin.
People are very respectful. Some have been shedding tears. Some people stopping, showing their children, as if they want them to know about this history. One man can be seen carrying a baby in his arms past the Queen’s coffin.
I was struck by older people going past, some infirm, who have waited for such a long time. And it meant so much to them because she has been monarch for most of their lives.
'Met police have monumental task' - ex-Secret Service agent
Timothy Miller, a security specialist and former US Secret Service agent, told the BBC that the Metropolitan Police have a "monumental task ahead of them" for the Queen's funeral.
When asked about whether US President Joe Biden would be travelling without Air Force One or his motorcade, he said it was not a "realistic possibility".
"The president of the US must be able to react within minutes to potential threats against the nation. As the leader that he is, he must have access to Air Force One for a number of security reasons, but also motorcade travel is important. The Secret Service is very sensitive on the requirements that they have," he told the World Tonight programme.
Miller said there would be unique security challenges.
"There will be a lot of heads of state in a single location and that's a dangerous security situation." he said.
Watch: How the day unfolded
Speeches at Westminster and Holyrood, a procession through the streets of Edinburgh, and queues to see the Queen at St Giles' Cathedral - it's been another hectic day.
You can watch a full round-up of all Monday's events here:
Video content
Night trains during Queen mourning period
Katy Austin
Transport correspondent
The group that represents train companies has confirmed trains will run through the night on some routes to help people travel to pay their respects to the late Queen, but that this offer will be "very limited".
A Rail Delivery Group spokesperson said: "The rail industry is doing all it can to ensure people can travel to pay their respects during the period of mourning.
"Where possible we will be running some extra services and customers should check journey planners for the most up to date information."
On night trains specifically: "A very limited service will be operating through the night on some routes, people should check journey planners for details."
It’s not currently clear exactly when this period will start or end.
Man arrested in Edinburgh after procession
Police Scotland have announced that a 22-year-old man was arrested on Monday in connection with a breach of the peace on the Royal Mile in Edinburgh.
Footage posted on social media show a man yelling at the funeral procession through Scotland's capital, which included all four of the Queen's children.
After heckling the procession he was pulled back and removed from the crowd by police.
It's not the only incident involving demonstrators. A woman bearing a sign reading "Not my King" was moved away from the Palace of Westminster by officers on Monday, while a 22-year-old woman was arrested outside Edinburgh's St Giles' Cathedral on Sunday.
She has been released from custody but is due in court at a later date.
Getty ImagesCopyright: Getty Images Officers move the demonstrator on from the Palace of Westminster in LondonImage caption: Officers move the demonstrator on from the Palace of Westminster in London
Queen was bright and focused in last audience - Boris Johnson
Video content
The former Prime Minister Boris Johnson has told the BBC the Queen was "absolutely on it" in their last meeting before his resignation as prime minister last week, just two days before her death.
"She was actively focused on geopolitics, on UK politics, quoting statesmen from the '50s, it was quite extraordinary. And she seemed very bright, very focused," he told BBC presenter Fiona Bruce.
"Given how ill she obviously was, how amazing it was that she be so bright and focused. It was a pretty emotional time."
When her death was announced two days later, he said he was moved by the Queen's "sense of duty".
Read more on the story here.
King's trips suggest the Union is a priority
Allan Little
Special correspondent
That the King has chosen to begin his reign with visits to Edinburgh, Belfast and Cardiff is telling.
It suggests that the future of the Union is at the heart of his concerns.
The early decades of his late mother's reign were characterised by the long, slow contraction of British Imperial power around the world.
He will be alert to the possibility that his own reign could come to be defined by the continuation of that process here - and the eventual dissolution of the United Kingdom itself.
Watch: King and siblings hold vigil by Queen's coffin
Video content
The Queen's children carried out the traditional Vigil of the Princes around the coffin of their late mother in St Giles' Cathedral, Edinburgh, earlier this evening.
The symbolic move sees four people position themselves at each side of the coffin to stand guard for a short time - today's event lasted 10 minutes.
King Charles III took up the role alongside his three siblings, the Princess Royal, the Duke of York and the Earl of Wessex.
What happens next?
Following the Vigil of the Princes, the Queen's coffin will continue to rest at St Giles' Cathedral in Edinburgh until 17:00 BST on Tuesday.
It will be moved from Edinburgh to the city's airport, where it will then be flown to RAF Northolt in west London at 18:00.
The Princess Royal, Princess Anne, will accompany the coffin, as she has since the beginning of its journey from Balmoral.
The coffin is expected to arrive in London at 19:00, and will then travel to Buckingham Palace, where it will be met by King Charles III and Camilla, Queen Consort.
The King and his wife will continue their tour of the nations tomorrow by visiting Belfast, where the monarch will meet Secretary of State for Northern Ireland, Chris Heaton-Harris, as well as other party leaders.
After a meeting with religious leaders, the royal couple will attend a prayer service at St Anne's Cathedral before travelling to London.
You can read about the day's proceedings in more detail here.
Mourners 'extremely moved' by moment beside the Queen's coffin
About 20,000 people have been waiting in a mile-long queue for several hours to enter St Giles' Cathedral in Edinburgh, where the Queen's coffin lies at rest.
William MacDonald, 63, from Edinburgh, says he was "extremely moved" by the experience of finally getting to pay his respects.
“It was beautiful,” he says. “Everything was done so well. I will never forget it. It was mind-blowing.
“She has been the best Briton ever, along with Winston Churchill.
"I am a bit star-struck.”
Rodney Matthews, a retired Baptist minister and member of Old Saint Paul's, a Scottish Episcopal Church in the heart of Edinburgh, says there was a sense of serenity about the event.
“You were able to move very slowly through, there was no rush at all," he says.
“There’s a moment where you can actually stand there and take it all in, the dignity of the whole place.
“It was very well done, very well organised once you go through security and get that feeling of space.”
In pictures: Charles, Anne, Andrew and Edward stand vigil
After a poignant 10 minutes, the vigil has now come to an end, with the Royal Family returning to their cars to applause from the crowd outside the cathedral.
BBCCopyright: BBC All four of the Queen's children - including King Charles III - stood around her coffin in EdinburghImage caption: All four of the Queen's children - including King Charles III - stood around her coffin in Edinburgh 
BBCCopyright: BBC The Princess Royal is the first woman to take part in the Vigil of the PrincesImage caption: The Princess Royal is the first woman to take part in the Vigil of the Princes 
BBCCopyright: BBC The Duke of York, Prince Andrew, closes his eyes during the vigilImage caption: The Duke of York, Prince Andrew, closes his eyes during the vigil 
BBCCopyright: BBC The Earl of Wessex, Prince Edward, stands beside his mother's coffinImage caption: The Earl of Wessex, Prince Edward, stands beside his mother's coffin
The Queen's children take their places
As we reported earlier, the Queen's four children are performing the traditional Vigil of the Princes around the coffin of their late mother at St Giles' Cathedral.
The symbolic move sees four people - in this case King Charles III, Princess Anne and Princes Andrew and Edward - position themselves at each side of the coffin to stand guard for a short time.
The Princess Royal's appearance makes her the first woman to be part of the vigil, which has until now been carried out by male-only members of the Royal Family.
When the Queen Mother died, her four grandsons carried out the duty - Charles, Andrew, Edward and David Armstrong-Jones, Princess Margaret's only son.
King and Queen Consort arrive for vigil
King Charles III and Camilla, Queen Consort, are now arriving at St Giles' Cathedral where they will hold a vigil for the Queen.
Huge policing effort for UK-wide events
Frank Gardner
BBC News, Security Correspondent
We've seen big crowds in Edinburgh today as the Queen lies at rest in St Giles' Cathedral - and yet more are expected once her coffin arrives to London tomorrow.
The primary concern for the police and security services over the coming days is public order rather than a terrorist threat.
The Metropolitan Police is leading on this, working closely with Police Scotland and the security service, MI5. They have rehearsed extensively for this week.
The current UK terror threat level remains at "substantial", meaning a terrorist attack is thought to be likely, but not highly likely or imminent - which would be two levels above where we are now.
The police are not aware of any specific terrorist threat to events marking the death of the Queen and there has been no noticeable increase in chatter amongst extremist groups or individuals.
That said, I’m told "no-one is going to breathe easy until these events are behind us" - and a number of Armed Response Vehicles (ARVs) are parked up in side roads in central London.
Tears and hugs as mourners file past Queen's coffin
A stream of mourners has been queueing in the late summer sunshine to enter St Giles' Cathedral in Edinburgh, where the Queen's coffin lies at rest.
They collected wristbands about a mile away at a station in The Meadows park earlier on, before queueing through the main University of Edinburgh area of the city to reach the cathedral.
King Charles to stand vigil by mother's coffin
Coming up, King Charles III will be back at St Giles' Cathedral in Edinburgh to hold a vigil for his late mother.
He'll stand by one corner of the raised platform - or catafalque - that her coffin is resting on. His siblings are expected to position themselves at the other three.
The process - called the Vigil of the Princes - was first carried out in 1936 when King Edward VIII and his three brothers, Princes Albert, Henry and George, stood by the coffin of their late father, King George V.
Since then, it has only been done on one other occasion - at the funeral of the Queen Mother in 2002. The King - who was known then as Prince Charles - was one of the people who stood by on that occasion.
Watch: Queen's coffin placed in St Giles' Cathedral
Video content
The Queen's coffin is now at rest on a catafalque - a raised platform - in St Giles' Cathedral, Edinburgh.
It was carried in, after the procession down the Royal Mile, by the Royal Regiment of Scotland.
Mourners begin to see Queen's coffin
This is the moment some in Edinburgh have been waiting for all day - the chance to view the Queen's coffin and pay their respects.
Wheelchair users have been given priority and have begun entering the cathedral.
Some people have been queueing since before 7am to ensure they get a wristband.
Officers of the King's Body Guard for Scotland are standing guard around the Queen's coffin - King Charles will stand vigil next to it later this evening.